The present invention relates to a method for setting up a data transmission connection as set forth in the preamble of claim 1. The invention relates also to a communication device as set forth in the preamble of claim 10.
Local area networks usually consist of one or more server computers as well as work stations and other peripheral devices communicating with the same, such as printers and telecopiers. Communication in a local area network is usually implemented in a wired manner, e.g. by Ethernet cabling. Also wireless local area networks are known, where data transmission is implemented by means of radio modems, thereby reducing limitations relating to the placement of cabling, number of connection points and their positioning in a wired local area network.
In local area networks, each peripheral device coupled to the local area network has an address identifying the peripheral device, i.e. client, whereby data is directed to this peripheral device. On the other hand, information from the peripheral device is recognised by the server on the basis of the address of the peripheral device. The peripheral device and the server are equipped with a network adapter determined on the basis of the physical structure of the local area network used at the time, comprising means for receiving messages from the local area network and for transmitting messages to the local area network.
Communication between different communication devices in local area networks usually takes place as data transmission based on messages. A message consists of address data and the actual information to be transmitted. The address data is used for directing messages to the correct device and, on the other hand, for identifying the device that transmitted the message.
Wireless local area networks differ from wired ones primarily in that the data transmission takes place by using a wireless communication method, e.g. by means of radio waves, infrared or inductive data transmission. In the operation, wireless local area networks are typically star networks, i.e. information is transmitted between a server device and a peripheral device. Thus, the information to be transmitted between peripheral devices is conducted from the transmitting peripheral device to the server device which transmits the information further to the receiving peripheral device.
In view of the operation of the local area network, the server device must know which peripheral devices are coupled to it at each time and what is the operating status of these peripheral devices. This can be implemented by using, for example, the above-mentioned communication based on messages, whereby in connection with turning on and a possible change of state, the peripheral device transmits a message to the server device. The server device receives the message and examines the information content of the message.
A local area network is suitable for use e.g. in offices, whereby data is transmitted by using a compact data processor with a sufficient storage capacity. An example of such a portable device is the Nokia 9000 Communicator which can be used both as a mobile station and as a data processor.
When using a wired communication network, also a portable data processor can be connected with a local area network by means of a network interface card, known as such and comprising means for setting up a data transmission connection between the local area network and the portable device. To portable data processors, it is possible to connect different peripheral devices directly without the need of a local area network. The connection can also be based on wireless techniques, usually the infrared technique (IR). By coupling such a peripheral device to a portable data processor or the like, the data of the peripheral device in question in the data processor must be configured before the peripheral device can be used.
Data transmission between different communication devices, such as servers and the clients of servers, in so-called piconets often takes place by means of short distance infrared (IR) data transmission, low power radio frequency (LPRF) data transmission, short distance radio frequency (SDRF) or inductive data transmission, whereby the data transmission distances within the local area network consisting of a single piconet are typically only a few metres or dozens of metres.
In addition to local area networks, wide wireless communication networks are known, such as the public land mobile network (PLMN) which is a communication network based on a cellular system. As an example, one could mention the GSM-900 mobile communication network based on the GSM system (Global System for Mobile Communication). The cells of the communication network are distributed in a wide geographical area, and mobile stations (MS), such as mobile phones, which communicate with the communication network by means of base stations (BS), move from one cell to another. These mobile stations are separated from each other by means of a subscriber-specific identification code, whereby data transmission between two mobile stations, such as data transfer or an audio call, is possible. The identification code used is e.g. the IMSI code (International Mobile Subscriber Number). The communication network takes care of routing information between base stations and mobile services switching centres (MSC) by utilising registration data on the location of the mobile station in the area of the cells of different base stations. Wireless communication networks include also GSM-1800, GSM-1900, PDC, CDMA, US-TDMA, IS-95, USDC (IS-136), iDEN (ESMR), DataTAC, and Mobitex.
For completing data transmission and processes related to data transmission by data processors connected in a local area network, such as servers and clients, for example peripheral devices and possibly also wireless communication devices, there must be a collection of communication rules available, determining the allowed messages and the operation of the communicating parties at different stages of the communication.
One such collection of communication rules is, in a known manner, a protocol, i.e. a practice whereby devices communicate with each other. For data transmission particularly in wireless communication networks, a wireless application protocol (WAP) has been developed, and this will be used as an example in the following description. In a known manner, one version of the WAP application protocol is described e.g. in the publication WAP Architecture Draft Version 0.9 (1997-09) published in the Internet network, describing e.g. the architecture of the WAP application protocol. By means of the WAP application protocol, it is possible to define a series of protocols at different levels, whereby it is possible to develop new services and devices for present and future wireless communication networks, e.g. mobile communication networks based on a digital cellular network. The WAP application protocol has been already developed e.g. for the short messaging service (SMS), unstructured supplementary service data (USSD), circuit switched data (CSD) and global packet radio system (GPRS) services of the GSM network.
It is an aim of the present invention to achieve a system that, by means of a local area network, makes connections to data processors, such as servers, clients of the servers, or them both, possible for conducting data transmission. The purpose of the invention is particularly to define a system for communication between a WAP server and a WAP client complying with the WAP application protocol in the area of a piconet utilising IR or SPRF services and utilising this piconet. The method of the invention is characterised in what will be presented in the preamble of the appended claim 1. The communication device of the invention is characterised in what will be presented in the preamble of the appended claim 10.
The application layer of the architecture of the above-mentioned WAP application protocol applies a defined wireless application environment (WAE) architecture. The different WAE applications of communication devices follow closely the protocol used in the Internet World Wide Web (WWW), where different applications and information is presented by means of standardised presentation formats which are browsed e.g. by means of known WWW browsers. Thus, the servers and information in the WWW network are named according to a Uniform Resource Locator (URL) address complying with the Internet standard and independent of the location, and the information presentation format is one that is supported by the browser used, for example Hyper Text Markup Language (HTML) or JavaScript.
It is an advantage of the method according to the invention to make it possible for the clients and servers of the local area network, the clients and servers of another local area network, and particularly the clients and servers temporarily within the area of the local area network to communicate and to use different services. This results from the elimination of drawbacks caused by differences in the addresses and addressing used in different communication networks. For example, the addressing of different nodes in a piconet differs from the addressing of nodes applying the WAP application protocol, whereby it is necessary to map the address used by the WAP application protocol to the corresponding address used by the piconet or to a temporary address created by the piconet.
By means of said mapping, a correspondence is established between e.g. so-called logical addresses, such as URL addresses, used by WAP applications, and physical addresses of the network, i.e. network addresses, used by the piconet. The network address is typically a nonstandardised network-specific numerical code which is reserved for a device by the server for creating the network and which is only useful in the area of said network. A logical address indicates in this context also the address of clients, i.e. communication devices, which is typically independent of the location and by means of which the communication device can be identified even in several different communication networks, in which the communication device is arranged to be operable. It should also be noticed that clients as well as services can be independent of the physical communication device, whereby the logical address can only be used to indicate e.g. a service, irrespective of the communication device where it is located. The communication network must thus take care of the addressing also for finding the correct device.
The invention gives significant advantages to both local area networks of prior art, based on short distance data transmission, and mobile communication networks based on a cellular network. For example, by using piconets applying the method, it is possible to create entirely novel local area network systems and local area network services which may include local access points e.g. to airport servers for inquiring flight schedules, retrieving airport services by means of pull-type data transmission, and information delivery by means of push-type data transmission to the communication devices of clients of the server in the area of the piconet.
Other possibilities include information delivery to the communication devices of clients by broadcast-type data transmission, remote control of PC systems in a piconet, and local connection points to gateway servers, whereby the connections e.g. to the Internet network and retrieving information from the Internet network is possible. Further, one could mention a guiding system based on the location of the client in the piconet, whereby the client is guided from one piconet to another. This is based on the small size of the coverage area of the piconet, whereby the location of the client placed in it is known relatively well.
The piconets described above are more suitable than a mobile communication network, such as the GSM network, to be used particularly for utilising the precise location of the client e.g. in connection with guiding systems or when the network operator offers services dependent on the location of the client. Piconets can be used also when it is desired that the client is not charged for data transmission for using services of the communication network as is usually the case in mobile communication networks. In case of circuit-switched data transmission, the open connection complying with the WAP application protocol usually prevents other communication by the communication device, such as ordinary audio calls, which can be avoided by using piconets.
According to an advantageous embodiment of the method of the invention, WAP servers and gateway WAP servers can announce their existence to WAP clients, such as wireless mark-up language (WML) browsers, which are transferred to the area of the piconet where also the WAP server or gateway WAP server is placed. Furthermore, the WAP servers can detect when a WAP client has moved into the area of the piconet, whereby push-type data transmission can be started by the WAP server.
According to another advantageous embodiment of the method of the invention, WAP clients can detect different WAP servers in the piconet into whose area the WAP client has moved. Thus, WAP clients operating in also other communication networks, such as a mobile communication network, can select the piconet as the communication network to be used and select e.g. the IR or LPRF data transmission mode. Thus, the communication devices of WAP clients can alternatively use the piconet for data transmission.
The method of the invention gives also the advantage of reduced data transmission costs, if the use of services in the piconet is free or the use of services has a very inexpensive charge. Furthermore, the power consumption of the communication devices can be lower in the piconet, because the piconet is typically a communication network with a small transmission output power and consequently a short range.
A further advantage of the method of the invention is that when any of the operations of a device can be remote-controlled, the remote control unit used can be the WAP client comprising means for connection to the piconet. Thus, the remote controlled device comprises means for connecting to the piconet and, further, this device is used as a WAP server in the piconet to make the remote control possible.